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-rwxr-xr-xscripts/link-vmlinux.sh375
1 files changed, 375 insertions, 0 deletions
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
new file mode 100755
index 000000000..acd07a70a
--- /dev/null
+++ b/scripts/link-vmlinux.sh
@@ -0,0 +1,375 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# link vmlinux
+#
+# vmlinux is linked from the objects selected by $(KBUILD_VMLINUX_OBJS) and
+# $(KBUILD_VMLINUX_LIBS). Most are built-in.a files from top-level directories
+# in the kernel tree, others are specified in arch/$(ARCH)/Makefile.
+# $(KBUILD_VMLINUX_LIBS) are archives which are linked conditionally
+# (not within --whole-archive), and do not require symbol indexes added.
+#
+# vmlinux
+# ^
+# |
+# +--< $(KBUILD_VMLINUX_OBJS)
+# | +--< init/built-in.a drivers/built-in.a mm/built-in.a + more
+# |
+# +--< $(KBUILD_VMLINUX_LIBS)
+# | +--< lib/lib.a + more
+# |
+# +-< ${kallsymso} (see description in KALLSYMS section)
+#
+# vmlinux version (uname -v) cannot be updated during normal
+# descending-into-subdirs phase since we do not yet know if we need to
+# update vmlinux.
+# Therefore this step is delayed until just before final link of vmlinux.
+#
+# System.map is generated to document addresses of all kernel symbols
+
+# Error out on error
+set -e
+
+LD="$1"
+KBUILD_LDFLAGS="$2"
+LDFLAGS_vmlinux="$3"
+
+# Nice output in kbuild format
+# Will be supressed by "make -s"
+info()
+{
+ if [ "${quiet}" != "silent_" ]; then
+ printf " %-7s %s\n" "${1}" "${2}"
+ fi
+}
+
+# Link of vmlinux.o used for section mismatch analysis
+# ${1} output file
+modpost_link()
+{
+ local objects
+
+ objects="--whole-archive \
+ ${KBUILD_VMLINUX_OBJS} \
+ --no-whole-archive \
+ --start-group \
+ ${KBUILD_VMLINUX_LIBS} \
+ --end-group"
+
+ ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${objects}
+}
+
+objtool_link()
+{
+ local objtoolopt;
+
+ if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then
+ objtoolopt="check"
+ if [ -n "${CONFIG_CPU_UNRET_ENTRY}" ]; then
+ objtoolopt="${objtoolopt} --unret"
+ fi
+ if [ -z "${CONFIG_FRAME_POINTER}" ]; then
+ objtoolopt="${objtoolopt} --no-fp"
+ fi
+ if [ -n "${CONFIG_GCOV_KERNEL}" ]; then
+ objtoolopt="${objtoolopt} --no-unreachable"
+ fi
+ if [ -n "${CONFIG_RETPOLINE}" ]; then
+ objtoolopt="${objtoolopt} --retpoline"
+ fi
+ if [ -n "${CONFIG_X86_SMAP}" ]; then
+ objtoolopt="${objtoolopt} --uaccess"
+ fi
+ if [ -n "${CONFIG_SLS}" ]; then
+ objtoolopt="${objtoolopt} --sls"
+ fi
+ info OBJTOOL ${1}
+ tools/objtool/objtool ${objtoolopt} ${1}
+ fi
+}
+
+# Link of vmlinux
+# ${1} - output file
+# ${2}, ${3}, ... - optional extra .o files
+vmlinux_link()
+{
+ local lds="${objtree}/${KBUILD_LDS}"
+ local output=${1}
+ local objects
+ local strip_debug
+
+ info LD ${output}
+
+ # skip output file argument
+ shift
+
+ # The kallsyms linking does not need debug symbols included.
+ if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
+ strip_debug=-Wl,--strip-debug
+ fi
+
+ if [ "${SRCARCH}" != "um" ]; then
+ objects="--whole-archive \
+ ${KBUILD_VMLINUX_OBJS} \
+ --no-whole-archive \
+ --start-group \
+ ${KBUILD_VMLINUX_LIBS} \
+ --end-group \
+ ${@}"
+
+ ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \
+ ${strip_debug#-Wl,} \
+ -o ${output} \
+ -T ${lds} ${objects}
+ else
+ objects="-Wl,--whole-archive \
+ ${KBUILD_VMLINUX_OBJS} \
+ -Wl,--no-whole-archive \
+ -Wl,--start-group \
+ ${KBUILD_VMLINUX_LIBS} \
+ -Wl,--end-group \
+ ${@}"
+
+ ${CC} ${CFLAGS_vmlinux} \
+ ${strip_debug} \
+ -o ${output} \
+ -Wl,-T,${lds} \
+ ${objects} \
+ -lutil -lrt -lpthread
+ rm -f linux
+ fi
+}
+
+# generate .BTF typeinfo from DWARF debuginfo
+# ${1} - vmlinux image
+# ${2} - file to dump raw BTF data into
+gen_btf()
+{
+ local pahole_ver
+
+ if ! [ -x "$(command -v ${PAHOLE})" ]; then
+ echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
+ return 1
+ fi
+
+ pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
+ if [ "${pahole_ver}" -lt "116" ]; then
+ echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
+ return 1
+ fi
+
+ vmlinux_link ${1}
+
+ info "BTF" ${2}
+ LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1}
+
+ # Create ${2} which contains just .BTF section but no symbols. Add
+ # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
+ # deletes all symbols including __start_BTF and __stop_BTF, which will
+ # be redefined in the linker script. Add 2>/dev/null to suppress GNU
+ # objcopy warnings: "empty loadable segment detected at ..."
+ ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
+ --strip-all ${1} ${2} 2>/dev/null
+ # Change e_type to ET_REL so that it can be used to link final vmlinux.
+ # Unlike GNU ld, lld does not allow an ET_EXEC input.
+ printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none
+}
+
+# Create ${2} .S file with all symbols from the ${1} object file
+kallsyms()
+{
+ local kallsymopt;
+
+ if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
+ kallsymopt="${kallsymopt} --all-symbols"
+ fi
+
+ if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
+ kallsymopt="${kallsymopt} --absolute-percpu"
+ fi
+
+ if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
+ kallsymopt="${kallsymopt} --base-relative"
+ fi
+
+ info KSYMS ${2}
+ ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2}
+}
+
+# Perform one step in kallsyms generation, including temporary linking of
+# vmlinux.
+kallsyms_step()
+{
+ kallsymso_prev=${kallsymso}
+ kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
+ kallsymso=${kallsyms_vmlinux}.o
+ kallsyms_S=${kallsyms_vmlinux}.S
+
+ vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
+ kallsyms ${kallsyms_vmlinux} ${kallsyms_S}
+
+ info AS ${kallsyms_S}
+ ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
+ ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
+ -c -o ${kallsymso} ${kallsyms_S}
+}
+
+# Create map file with all symbols from ${1}
+# See mksymap for additional details
+mksysmap()
+{
+ ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
+}
+
+sorttable()
+{
+ ${objtree}/scripts/sorttable ${1}
+}
+
+# Delete output files in case of error
+cleanup()
+{
+ rm -f .btf.*
+ rm -f .tmp_System.map
+ rm -f .tmp_vmlinux*
+ rm -f System.map
+ rm -f vmlinux
+ rm -f vmlinux.o
+}
+
+on_exit()
+{
+ if [ $? -ne 0 ]; then
+ cleanup
+ fi
+}
+trap on_exit EXIT
+
+on_signals()
+{
+ exit 1
+}
+trap on_signals HUP INT QUIT TERM
+
+# Use "make V=1" to debug this script
+case "${KBUILD_VERBOSE}" in
+*1*)
+ set -x
+ ;;
+esac
+
+if [ "$1" = "clean" ]; then
+ cleanup
+ exit 0
+fi
+
+# We need access to CONFIG_ symbols
+. include/config/auto.conf
+
+# Update version
+info GEN .version
+if [ -r .version ]; then
+ VERSION=$(expr 0$(cat .version) + 1)
+ echo $VERSION > .version
+else
+ rm -f .version
+ echo 1 > .version
+fi;
+
+# final build of init/
+${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
+
+#link vmlinux.o
+info LD vmlinux.o
+modpost_link vmlinux.o
+objtool_link vmlinux.o
+
+# modpost vmlinux.o to check for section mismatches
+${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
+
+info MODINFO modules.builtin.modinfo
+${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
+info GEN modules.builtin
+# The second line aids cases where multiple modules share the same object.
+tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
+ tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
+
+btf_vmlinux_bin_o=""
+if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
+ btf_vmlinux_bin_o=.btf.vmlinux.bin.o
+ if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
+ echo >&2 "Failed to generate BTF for vmlinux"
+ echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
+ exit 1
+ fi
+fi
+
+kallsymso=""
+kallsymso_prev=""
+kallsyms_vmlinux=""
+if [ -n "${CONFIG_KALLSYMS}" ]; then
+
+ # kallsyms support
+ # Generate section listing all symbols and add it into vmlinux
+ # It's a three step process:
+ # 1) Link .tmp_vmlinux1 so it has all symbols and sections,
+ # but __kallsyms is empty.
+ # Running kallsyms on that gives us .tmp_kallsyms1.o with
+ # the right size
+ # 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of
+ # the right size, but due to the added section, some
+ # addresses have shifted.
+ # From here, we generate a correct .tmp_kallsyms2.o
+ # 3) That link may have expanded the kernel image enough that
+ # more linker branch stubs / trampolines had to be added, which
+ # introduces new names, which further expands kallsyms. Do another
+ # pass if that is the case. In theory it's possible this results
+ # in even more stubs, but unlikely.
+ # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
+ # other bugs.
+ # 4) The correct ${kallsymso} is linked into the final vmlinux.
+ #
+ # a) Verify that the System.map from vmlinux matches the map from
+ # ${kallsymso}.
+
+ kallsyms_step 1
+ kallsyms_step 2
+
+ # step 3
+ size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
+ size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
+
+ if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
+ kallsyms_step 3
+ fi
+fi
+
+vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
+
+# fill in BTF IDs
+if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then
+ info BTFIDS vmlinux
+ ${RESOLVE_BTFIDS} vmlinux
+fi
+
+if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then
+ info SORTTAB vmlinux
+ if ! sorttable vmlinux; then
+ echo >&2 Failed to sort kernel tables
+ exit 1
+ fi
+fi
+
+info SYSMAP System.map
+mksysmap vmlinux System.map
+
+# step a (see comment above)
+if [ -n "${CONFIG_KALLSYMS}" ]; then
+ mksysmap ${kallsyms_vmlinux} .tmp_System.map
+
+ if ! cmp -s System.map .tmp_System.map; then
+ echo >&2 Inconsistent kallsyms data
+ echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
+ exit 1
+ fi
+fi